Manufacture of high viscosity index lubricating oil of low pour test



characterized by having a relatively narrow in- Patented Mar. 19, 1935' UNITED STATES MANUFACTURE OF HIGH VISCOSITY INDEX LUBBICATING 01L OF LOW POUR TEST Francis X. Govers, Vincennes, Ind., assignor to Indian Refining Company, Lawrcnceville, 111., a corporation of- Maine No Drawing. Application March 9, 1933, Serial No. 660,098

This invention relates to the manufacture of mineral lubricating oils and more particularly to the manufacture of high viscosity index, low pour test lubricating oil from wax bearing mineral oils.

In its broadest aspect, the invention contemplates an improved process of treating hydrocarbon oils, particularly paraffin-bearing lubricating fractions of petroleum with solvents to selectively produce therefrom low pour test lubricating oils characterized by having a desired viscosity temperature relationship and improved lubricating qualities The invention contemplates a process of manufacturing lubricating oils having low pour and .cloud tests, low sulphur content, low Conradson carbon content, relatively high viscosity index and freedom from bodies of little or no lubricating value.

Lubricating oils, as ordinarily made from naphthene-base crudes, have low pour and cloud tests, low Conradson carbon content, but have low viscosity indices and fairly high sulphur content. On the other hand, lubricating oils, as ordinarily made from parafiin-base crudes of the Pennsylvania type, have high pour and cloud tests, high Conradson carbon content and fairly high sulphur content, depending on the source of particular crude used. Oils derived from mixed base crudes fall somewhere between these limits although usually high in sulphur content. Oils of the Pennsylvania type, as well as those derived from mixed base crude sources, are difiicult to refine without undue loss and impairment of their lubricative value. In all cases, it is difficult, by methods now employed, to reduce the sulphur content of these lubricating oil fractions 'to a desired point, regardless of their source of crude.

I have discovered that by the use of the methods herein disclosed lubricating oils of any desired viscosity index and scale of purification coupled with low pour test and low cloud test, can be made from mixed-base or paramn base crudes and the oils so produced are characterized further by low Conradson carbon and low sulphur content. The obtaining of oils having these desired qualities does not depend on methods involving redistillation or acid treatment, although such redistillation or acid treatment can be cou-' pled with the methods herein disclosed if so de- Lub'ricating oils of high viscosity index are crease in viscositywith respect to temperature. Such oils have the property of possessing the desired viscosity at elevated temperature with not too great a loss of mobility at very low temperature. The viscosity index of a given oil is readily determined by resorting to the method of Dean and Davis, published on pages 618-619 of 5 the 1929 issue of Chemical and Metallurgical Engineering.

More specifically the invention comprises mix-' ing with a wax-bearing fraction of a mineral oil a solvent mixture composed of benzaldehyde and a modifying solvent selected from the group comprising isopropyl ether,.ethyl ether, benzol, toluol, and the like, in such proportion to each other and to the oil that the mixture has substantially complete solvent action on the oil at temperatures of around 100 F., and at temperatures of around 0? F. substantially complete solvent action on the liquid hydrocarbons therein but substantially no solvent action on the solid hydrocarbons therein and of such a nature that upon cooling a solution of the mineral oil fraction in such solvent mixture to UP F. and removing the solid hydrocarbons so precipitated and the solvent liquid the resulting oil has a cold test of substantially 0 F.

or below. 1

The mixture is then chilled to form a precipitate of solid or semi-solid material comprising suspended wax or solid hydrocarbons which are insoluble in, and immiscible with, the desired solvent mixture. The mother liquor is separated from the chilled mixture, advantageously by filtration. The separated mass of solid'hydrocarbons is then washed free of mother liquor containing dissolved oil by additional quantities of chilled solvent liquid of approximately the same composition as used in the original mix.

A portion of the first. part of this wash filtrate may be added to the original filtrate. The extent of such addition depending on the amount or percentage of oil contained in such wash filtrate.

' From the original filtrate or mixture of original filtrate and wash filtrate is then evaporated one of the component solvents in an amount sufficient to effect the desired alteration in the selective solvent action of the mixture.

This resulting mixture of altered composition may be cooled or chilled to still further aflect its percentage composition of the component'parts 6d comprising the solvent mix and the temperature to which such altered composition mixture is chilled. If desired the modifying solvent may be removed in successive stages, subjecting the remaining mixture of dissolved oil and solvent to cooling in each instance to thereby successively separate fractions of differing characteristics as may be desired.

It is contemplated that the wax-bearing fraction may be subjected to preliminary refining either with acid or by extraction with a suitable solvent such as the selective solvent component of the'mixture used in the subsequent steps. The resulting treated fraction is dewaxed by means of a chilled selective solvent mixture composed of the selective solvent and. a modifying solvent, followed by the separation of the dewaxed fraction into oils of differing viscosity indices by means of evaporation in whole or part of the modifying solvent. The solvent component may be benzaldehyde, or asolvent of like solvent nature and the modifying solvent may be isopropyl ether, ethyl ether, toluol, benzol, or a solvent of like solvent nature.

As an example of the process:

An acid treated wax distillate having the following approximate 26 B., viscosity of 70 Saybolt universal seconds at 210 F., and a pour test of 95 F. is well mixed with isopropyl ether. After the air in the mixture is displaced with carbon dioxide or other inert gas benzaldehyde is then added. The proportions of these two solvents used comprises about parts ether to 40% benzaldehyde. The mixture is-well stirred, chilled to 20 F., and while maintained in this chilled condition, introduced to a pressure type filter such as described in my copending application, Serial No. 585,844, wherein the solid hydrocarbons are separated to produce a filtrate substantially free from dissolved wax and solid hydrocarbons.

The filter cake, without removal from the filter, is washed with additional solvent liquid mixture of substantially the same composition and which has been chilled to a temperature of -20 F.

This wash filtrate is used for part of the solvent mixture in a succeeding batch, allowance being made for the oil contained therein.

The wax slurry is drawn off from the filter and the solventremoved by evaporation or distillation in a reducing or non-oxidizing atmosphere, such as carbon dioxide for example. The wax, free from solvent, is then steam treated in the presence of clayand contact filtered. The resulting wax is practically water white and will have a. melting point of approximately 138 F.

From the dewaxed filtrate the isopropyl ether is evaporated or distilled, while maintaining a non-oxidizing atmosphere. When the resulting mixture is cooled to about 30 FL and allowed to stand, separation into two layers occurs. The lower layer is drawn off and will contain oil of comparatively low viscosity index while the remaining top layer will contain oil of comparatively high viscosity index.

The invention is not limited to the production of final products to the percentages of or characteristics of those produced in the examples given above. Products of varying percentages and characteristics may be produced by varying the proportions of solvent liquids and their concentration and the temperature at which the treating steps are carried out.

Furthermore, the invention is not limited to the treatment of wax distillate such as given in characteristics, gravity the examples herein but is adapted to the treatment of other paraffin-containing fractions, pre-,

cipitates or materials somewhat similar in nature derived in various ways from mineral oils.

Thus my invention is applicable to the treatment of hydrogenation products resulting from the hydrogenation of carbonaceous materials, or

mineral oils including liquid or solid hydrocarbon The invention is not restricted to any particular operating condition such as that of temperature, or the composition of the solvent mixtures employed since these conditions may advantageously be varied, depending upon the nature of the fraction undergoing treatment as well as upon the particular characteristics desired in the final product. I

It is also contemplated, in many instances, that it may be of advantage to carry on the filtration step in the presence of a comminuted solid filteraid material. Such material may be admixed with the chilled mixture of oil and solvent liquid prior to introduction to the filtering means.

Obviously many modifications and variations of the invention, as hereinbefcre set forth, may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in th appended claims.

1. The process of manufacturing high viscosity index lubricating oil having a low pour test from wax-bearing mineral oil which comprises mixing with the oil a solvent liquid mixture composed of benzaldehydeand a modifying solvent liquid having substantially no selective action as between constituents of the oil of differing viscosity indices and in proportions with the oil such that at temperatures of around 0 F., the mixture has substantially complete solvent action on the oil and substantially no solvent action on the wax, chilling the mixture to precipitate wax constituents of the oil, removing the wax thus precipitated, removing from the resulting dewaxed mixture a suitable portion of the modifying solvent to thereby render the remaining solvent liquid selective as between constituents of the oil of differing viscosity index, and separating from the remaining mixture a. fraction of desired viscosity index and low pour test.

2. The process of manufacturing high viscosity index lubricating oil having a low pour test from wax-bearing mineral oil which comprises mixing with the oil a solvent liquid mixture composed of benzaldehyde and a modifying solvent liquid selected from the group consisting of isopropyl ether and ethyl ether, and in proportions with the oil such that at temperatures of around 0 F., the mixture has substantially complete solvent action on the oil and substantially no solvent action on the wax, chilling the mixture to precipitate wax constituents of the oil, removing the wax thus precipitated, removing from the resulting dewaxed mixture a suitable portion of and separating from the remaining mixture a fraction of desired viscosity index and low pour test. I

3. The process of manufacturing a low cold test lubricating oil from a wax-bearing fraction of a mineral oil which comprises mixing the said fraction with benzaldehydeand a modifying solvent having substantially no selective solvent action as between liquid constituents of the oil in such a ratio to each other and to said fraction that the benz'aldehyde and modifying solvent together, at temperatures of approximately 100 F., have substantially complete solvent action on such fraction, and at temperatures of 5 F. and belowhave substantially complete solvent action on the liquid hydrocarbons but substantially no solvent action on the solid hydrocarbons in said fraction, and upon removal of the solid hydrocarbons and the solvent liquids'such fraction has a cold test substantially the same as the temperature of the mixture at the time of the removal of the solid hydrocarbons, cooling the mixture to a temperature of F. or below, and removing .therefrom the solid hydrocarbons so precipitated.

4. The process of manufacturing a low cold test lubricating oil from a wax-bearing fraction of a mineral oil which comprises mixing the said fraction with benzaldehyde and a modifying solvent selected from the group consisting of isopropyl ether and ethyl ether, in such a ratio to each other and to said fraction that the benzaldehyde and modifying solvent together, at temperatures of approximately 100 F. have' substantially complete solvent action on such fraction, and at temperatures of F. and below have substantially complete solvent action onthe liquid hydrocarbons but substantially no solvent action on the solid hydrocarbons in said fraction, and upon removal of the solid hydrocarbons and the solvent liquids, such fraction has a cold test substantially the same as the temperature of the mixture at the time of the removal of the solid hydrocarbons, cooling the mixture to a temperature of "0 F. or below, and removing therefrom the solid hydrocarbons so precipitated.

5. The process of manufacturing a low cold test high viscosity index lubricating oil from a wax-bearing fraction of a. mineral oil which comprises mixing the said fraction with benzaldehyde and isopropyl ether in such proportions that at temperatures of around 0 F., the mixture has substantially complete solvent action on the oil and substantially no solvent action on the wax; cooling the mixture to precipitate wax constituents of the oil, removing the precipitated wax, removing from the dewaxed mixture suiihble portion of the isopropyl ether to thereby render the, remaining solvent liquid selective as between constituents of the oil of differing viscosity index,

and separating from the remaining mixture 9. fraction of desired viscosity index and low pour test.

' 6. In the process of improving the pour test, viscosity index and viscosity gravity constant of a wax-bearing fraction of a mineral oil which comprises extracting said fraction with a solvent mixture composed of benzaldehyde and a modifying solvent having substantially no selective solvent action as between constituents of the oil of differing viscosity indices in such proportions that at temperatures of around 0 F. the mixture has substantially complete solvent action on the oil and substantially no solvent action on the wax, chilling the mixture to precipitate wax constituents of the oil, and removing the wax thus precipitated, the method of effecting separation of the resulting dewaxed mixture into fractions of differing viscosity indices comprising evaporatively removing successive portions of said modifying solvent in stages, and, after each evaporation stage, regulating the temperature of the mixture so as to precipitate out successive fractions of oil of difiering viscosity index.

7. In the treatment of mineral oil containing naphthenic and paraflinic constituents including wax to separate the oil into fractions respectively rich in naphthenic and paraflinic constituents, the method comprising extracting the oil with 'benzaldehyde in the presence of a non-oxidizing atmosphere of the character of carbon dioxide.

I 8. The process according to claim 1 in which the oil is preliminarily extracted with a selective solvent comprising benzaldehyde.

9. The process according to claim 2 in which the oil is preliminarily extracted with a selective solvent comprising benzaldehyde.

10. The process according to claim 3 in which the oil is preliminarily extracted with a selective solvent comprising benzaldehyde.

l1.-The process of dewaxing wax-bearingmineral oil which comprises mixing the oil with a solvent liquid mixture composed of benzaldehyde and isopropyl ether in proportions such that at temperatures of 0 F. and below the mixture has substantially complete solvent action on the oil and substantially no solvent action on the wax, chilling the mixture to precipitate the wax, and removing the precipitated wax from the cold mixture.

12. The process of dewaxing wax-bearing mineral oil which comprises mixing the oil with a solvent liquid mixture composed of benzaldehyde and ethyl ether in proportions such that at temperatures of 0 F. and'below the mixture has substantially complete solvent action on theoil and substantially no solvent action on the wax, chilling the mixture to precipitate the wax, and removing the precipitated wax from the cold mixture.

13. The process according to claim 11 in which FRANCIS x. GOVERS 

